Objective:

To compare short and intermediate-term inpatient encounter rates following hospitalization for autoimmune encephalitis (AE) versus viral encephalitis (VE) using a large multicenter electronic health record database.

Background:

Autoimmune encephalitis and viral encephalitis are major causes of central nervous system inflammation requiring hospitalization. While their pathophysiology, clinical presentations, and management differ significantly, comparative data on post-hospitalization inpatient healthcare utilization are limited.

Design/Methods:

Using the TriNetX Network, we identified patients (≥18 years) hospitalized with a first diagnosis of AE (ICD-10: G04.81, G04.89) or VE (A86, B00.4, A85.8, G04.90). Cohorts were defined by the first instance of a qualifying ICD-10 code and an inpatient encounter on the same day. Patients with any occurrence of the opposite diagnosis were excluded. Propensity score matching was performed on age, sex, race, and ethnicity. Outcomes were defined as inpatient encounters occurring within three post-index windows: 1–15 days, 15–30 days, and 30–90 days as a proxy for continued index admission or readmissions following approximated discharge. 

Results:

7,198 to 8,960 patients were included for each cohort. In the 1-15 day window, AE vs. VE patients had a non-significant difference in inpatient encounter rates (20.4% vs. 21.5%; RR 0.95, 95% CI 0.89–1.006, p=0.08). In the 15–30 day window, AE patients had a significantly increased risk of inpatient encounters (10.4% vs. 9.2%; RR 1.13, 95% CI 1.03–1.24, p=0.011). In the 30–90 day interval, encounter rates were comparable between the groups (13.6% vs. 12.9%; RR 1.06, 95% CI 0.97–1.15, p=0.21).

Conclusions:

Among matched cohorts, AE was associated with a small but statistically significant increase in inpatient encounters between 15 and 30 days post-hospitalization compared to VE. This window was used as a proxy for readmission following discharge. This may reflect early AE recurrences in patients discharged without bridging immunotherapy. These findings suggest a potential need for intensified follow-up and transitional care strategies for AE patients.